RU2285120C2 - Device for measuring number of turns of shaft of face engine - Google Patents

Abstract

FIELD: drilling technologies, in particular, engineering of equipment for measuring frequency of rotation of turbo-drill shaft, or volumetric engine and can be used during driving of horizontal and inclined wells for receiving operative information during drill.

SUBSTANCE: device contains sensitive element, positioned on body, mechanically connected to shaft of face engine, and electronic circuit. Sensitive element is made in form of differential ferro-probe, mounted so that sensitive axis of ferro-probe was perpendicular to rotation axis of face engine shaft, and outputs of measuring winding of ferro-probe were connected to electronic circuit, realizing selection of maximums of amplitude of output EMF of differential ferro-probe and transformation of temporal period between them to number of turns.

EFFECT: simplified construction of sensitive element and decreased dimensions of device.

3 cl, 2 dwg

Description

The invention relates to the field of drilling, in particular to devices for measuring the rotational speed of a shaft of a downhole motor or a turbodrill, and can be used when drilling horizontal and directional wells to obtain operational information during drilling.

When using a wired and wireless communication channel as sensors for the rotational speed of a turbo-drill shaft, designs of electric machine alternators are widely used (Molchanov A.A. Measurement of geophysical and technological parameters in the process of drilling wells. - M .: Nedra, 1983. - P. 62- 64). The stator with windings is fixed motionless, and the rotor with permanent pole magnets is connected to the shaft of the turbodrill. The bit rotation frequency is defined as N = nf / 30, where f is the frequency of the current generated by the generator; n is the number of pole pairs.

The disadvantage of such sensors is the mechanical joint of the generator shaft with the turbo-drill shaft, as well as the relative complexity of the generator design, which reduces the reliability of the sensor when operating in conditions of strong vibrations.

Known speed sensors with non-contact connection of a rotation element with a sensitive element, for example, a turbodrill shaft revolution sensor (ed. St. USSR No. 197314, Bull. No. 12, 1967), comprising a ferromagnetic core with a measuring coil and a non-magnetic glass with ferromagnetic anchors, moreover, the ferromagnetic core with the measuring coil is molded inside the monolithic elastic rod, and for the purpose of fitting to the upper sub, it is equipped with a movable container included in the support pipe. The disadvantage of this sensor is its low manufacturability, due to the need to manually adjust the movable container to the length of the upper sub.

Also known is a turbo-drill shaft speed sensor according to ed. St. USSR No. 1420140 dated 10.11.86, containing a hollow cylindrical body, inside of which is placed a container with electronic equipment, a rod connected to the shaft of the turbodrill. The sensor has a cover made of insulating material, a permanent magnet eccentrically mounted on the rod, an inductor with a ferromagnetic core connected to electronic equipment. One of the poles of the permanent magnet is placed inside the rod, located inside the case of insulating material connected to the housing, in the wall of which there is an inductor, and the inductor and the rod are parallel to the axis of the sensor. At each revolution of the turbo-drill shaft, a voltage pulse is generated.

In the above sensor designs by ed. St. USSR No. 197314 and No. 1420140, the sensing element is located in the fixed part of the instrument construction. These sensors have a rather complicated design, which, if it is necessary to place a large number of sensors, is very difficult to install near the bit.

The closest in technical essence is a device for controlling the revolutions of a turbo-drill shaft, in which the sensitive element is located on a structural element rigidly fixed to the turbo-drill shaft (ed. St. USSR No. 560973 of 10/29/1974). The device contains a sensing element and a drive and vibration removal system, is equipped with a magnetic cup rigidly mounted on the shaft of the turbodrill, and the sensing element is made in the form of a top with a magnetic base mounted on the bottom of the magnetic cup, and the axis of the top is placed in an elliptical shape holder, in the gap of the system drive and removal of vibrations.

In this device, the sensitive element has a rather complicated structure, which is also problematic to install near the bit.

The present invention solves the problem of simplifying the design of the sensitive element and reducing the size of the device and allows you to place it in the immediate vicinity of the bit.

The essence of the invention consists in the use of a differential flux probe as a sensitive element in a device for measuring the number of revolutions of a shaft of a downhole motor.

It is known in the art to use flux-gates for measuring weak constant and slowly changing (with a frequency of not more than 100 Hz) magnetic fields for measuring the angles between the axes of an object and the magnetic induction vector, for detecting ferromagnetic objects, for measuring the magnetic susceptibility and magnetic moment of weakly magnetic substances (Levshina E .S., Novitsky P.V. Electrical Measurements of Physical Quantities: (Measuring Transducers). A Textbook for High Schools. - L .: Energoatomizdat. Leningrad Department, 1983. - S.209-211). However, differential probes were not used as a sensitive element in devices for measuring the number of revolutions of rotating elements.

When the differential flux-gate rotates synchronously with the engine, one of the components of the directivity vector of the Earth’s natural magnetic field coincides with the sensitivity axis of the flux-gate, which can be recorded in the flux-probe measuring coil as a change in the amplitude of the output emf.

In the proposed device for measuring the number of revolutions of the shaft of a downhole motor, comprising a sensing element located in a housing mechanically connected to the shaft of the downhole motor, and an electronic circuit, the sensing element is made in the form of a differential flux-gate mounted so that the axis of sensitivity of the flux-gate is perpendicular to the axis of rotation of the shaft downhole motor, and the outputs of the measuring winding of the flux gate are connected to an electronic circuit that selects the maximum amplitude of the output emf differential fluxgate and the conversion of the time period between them into a number of revolutions.

The electronic circuit contains a selective amplifier, a rectifying unit, a zero-organ, matching block and a microprocessor, while the outputs of the measuring coil of the flux-gate are connected to the input of the selective amplifier, the output of the amplifier is connected to the input of the rectifier block, and the output of the latter through a zero-organ is connected to the microprocessor conversion of the period following the maximum amplitude of the output emf differential flux-gate in the number of revolutions, as well as controlling the operation of the matching block and powering the differential flux-gate, for which the input of the matching block is connected to the microprocessor, and the outputs of the supply winding of the differential flux-gate are connected to the matching block.

The differential flux gate and the electronic circuit are located in a module installed between the downhole motor and the bit.

This solution allows you to get a simple in design and compact device that allows you to measure the number of revolutions of the shaft of the downhole motor with sufficient accuracy and install it near the bit.

In Fig.1 shows a block diagram of a device for measuring the number of revolutions of the shaft of a downhole motor, Fig.2 is a diagram of the location of the differential flux gate in the housing of the proposed device.

The proposed device contains a differential flux gate, consisting of two parallel ferrite rods 1, a supply winding 2 connected to a matching unit 3, and a measuring winding 4, the outputs of which are connected to the input of the selective amplifier 5. The output of the amplifier is connected to the input of the rectifier block 6, and the output the latter through a null-organ 7 is connected to the microprocessor 8. The microprocessor also controls the operation of the matching unit 3, for which the input of the matching unit is connected to the microprocessor. A differential flux probe is installed in the housing of a separate module (Fig. 2) so that the sensitivity axis 9 of the differential flux probe (passing through the maximum values of the radiation pattern shown in Fig. 2) is perpendicular to the rotation axis 10 of the shaft 11 of the downhole motor 12. To provide mechanical coupling, the housing 13 module screwed downhole motor. The module is located above the bit 14.

The device operates as follows.

An alternating voltage of a certain frequency, for example (2-3 kHz), which is generated by a microprocessor 8, is supplied to the supply winding 2 of the differential flux-gate through the matching block 3. During the rotation of the differential flux-gate, which occurs synchronously with the rotation of the shaft 11 of the downhole motor 12, in the measuring winding 4 creates an emf with a frequency of the supply voltage, the amplitude of which varies depending on the orientation of the flux gate in the Earth's magnetic field. Thus, the amplitude modulation of the output emf occurs. Earth’s magnetic field. When the flux-gate rotates twice in one revolution of the engine, one of the components of the directivity vector of the Earth’s natural magnetic field coincides with the sensitivity axis of the flux-gate, which are recorded on the flux-probe measuring coil with maximum values of the amplitude of the output emf.

Then the amplitude-modulated output emf from the output of the measuring winding 4, it is fed to a selective amplifier 5, which extracts the second harmonic of the incoming signal, is detected by the rectifier unit 6 and is fed to the input of the zero-organ 7. From the output of the zero-organ information is in the form of rectangular pulses, the transit time of which corresponds to the time period of the maximum amplitudes emf comes to the microprocessor 8, where the duration of the time period between rectangular pulses is calculated and converted to the number of revolutions of the shaft of the downhole motor la or turbodrill.

Claims (3)

1. A device for measuring the number of revolutions of a shaft of a downhole motor, comprising a sensing element located in a housing mechanically connected to the shaft of the downhole motor, and an electronic circuit, characterized in that the sensing element is made in the form of a differential flux-gate mounted so that the axis of sensitivity of the flux-gate is perpendicular to the axis of rotation of the shaft of the downhole motor, and the outputs of the measuring winding of the flux gate are connected to an electronic circuit that selects the maxima of the output amplitude emf differential fluxgate and the conversion of the time period between them into a number of revolutions. 2. The device for measuring the number of revolutions of the shaft of a downhole motor according to claim 1, characterized in that the electronic circuit contains a selective amplifier, a rectifier unit, a zero-organ, a matching unit and a microprocessor, while the outputs of the measuring winding of the differential flux probe are connected to the input of the selective amplifier, the output of the amplifier is connected to the input of the rectifier unit, and the output of the latter through a zero-organ is connected to a microprocessor that converts the period of the maximum amplitude of the output emf. the differential flux gate in the number of revolutions and also controlling the operation of the matching block and powering the differential flux gate, for which the input of the matching block is connected to the microprocessor, and the outputs of the supply winding of the differential flux gate are connected to the matching block. 3. The device for measuring the number of revolutions of the shaft of a downhole motor according to claim 1, characterized in that the differential fluxgate and the electronic circuit are located in a module installed between the downhole motor and the bit.

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